Polymerization of cyclic esters



United States Patent ()flfice 3,021,315 Patented Feb. 13, 1 962 3,021,315 POLYMERIZA'HON OF CYCLIC ESTERS Eugene F. Cox and Fritz Hostettler, Charleston, W. Va, assigners to Union Carbide Corporation, a corporation of New York No Drawing. Filed Dec. 3, 1959, Ser. No. 856,912 15 Claims. (Cl. 26078.3)

This invention relates to a process for polymerizing cyclic esters and to the products resulting therefrom.

The most generally familiar works on the polymerization of lactones are the now classical investigations of W. H. Carothers. For instance, Carothers was able to polymerize delta-valerolactone to poly-delta-valerolactone by heating at 8085 C. for a period of about 13 days, or by contacting delta-valerolactone with potassium carbonate catalyst at a temperature of 8085 C. for a period of about 5 days. The resulting polymers were soft waxes possessing average molecular weights of approximately 2000 which had relatively low thermal stabilities. The literature reports that attempts to polymerize gamma-butvrolactone have been unsuccessful, and the corresponding polyester is not known. fin-1934, there was reported the preparation of poly-epsiloncaprolactone by heating epsilon-caprolactone at about 150 C. for a period of 12 hours, or by contacting epsi oncaprolactone with potassium carbonate at about 150 C. for a period of 5 hours. The resulting epsilon-caprolactone polymers had melting points of about 53 --55v C. and average molecular weights of about 4000. The polymers were hard, brittle waxes which could not be coiddrawn into fibers. Bischoff and Waldon describe the transformation of glycolide under the influence of heat or a trace of zinc chloride into a polymeric solid melting at 220 C. On being distilled in a vacuum it was reconverted to the monomer melting at 8687 C. The

literature also reports the polymerization of lactide at polyrners, copolyrners, and terpolymers prepared by the practice of the instant invention are highly useful products as will become apparent at a later'section herein. In addition, the polymerization reaction can oftentimes be conducted at lower temperatures and at faster polymerization rates heretofore unattainable in lactone poly-v merization art.

Accordingly, one or more of the following objects will be achieved by the practice of this invention.

1 Collected Papers of Wallace vH. Cal-others, edited by H. Mark and G. S. Whitby, volume I, Interscience Publishers, Inc, New York (1940).

J. van Natta, J. W. Hill, and W. H. Carothers, J'our, Amer. Chem. Soc., 56, 455 (1934).

Ber. 36, 1200 (1903).

It is an object of this invention to provide a novel process for homopolymerizing"monomeric cyclic esters to produce useful homopolymers. It is another object of this invention to provide a novel process for polymerizing an admixture containing at least two different monomeric cyclic esters to produce useful polymers. A further object of this invention is to prepare lactone polymers having a high degree of utility and application in the cosmetic, wax, polish,thickening, coating, etc., fields. Other objects will become apparent to those skilled in the art in the light of the instant specification.

, In one embodiment the monomeric cyclic esters employed in the polymerization process of this invention can be characterized by the following formula:

ll C-O wherein each R, individually, can be hydrogen, alkyl, aryl, alkaryl, aralkyl, cycloalkyl, halo, haloalkyl, alkoxyalkyl, alkoxy, aryloxy, and the like; wherein A can be an oxy (O) group, a thio (S) roup, a divalent Saturated aliphatic hydrocarbon group, and the like; wherein x is an integer from 1 to 15 inclusive; wherein y is an integer from 1 to 15 inclusive; wherein z is an integer having a value of zero or one; with the provisos that (a) the sum of x+y+z cannot equal 3, (b) the total number of atoms forming the cyclic ester ring does not exceed 18, preferably does not exceed 9, (c) the total number oforganic substituents (such as those described for the R variables) attached to the carbon atoms contained in the cyclic ester ring does not exceed 4, preferably does not exceed 3, (d) from 2 to 4 continuously linked carbon atoms contained in the cyclic ester ring can represent a portion of a saturated cycloaliphatic hydrocarbon nucleus which 0 contains from 4 to 10 ring carbon atoms, and (e) the four R variables attached to any two adjacent carbon atoms contained in the'cvclic ester ring can represent a portion of a fused aromatic hydrocarbon nucleus.

With reference to Formula I supra, illustrative R radicals include, among others, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, t-butyl, amyl, the hexyls, the heptyls, the octyls, dodecyl, octadecyl, phenyl, benzyl, tolyl, xylyl, ethylphenyl, butylphenyl, phenethyl, phenylpropyl, phenylbutyl, cyclopentyl, 2-propylcyclohexyl, cyclohexyl, 2 -methy1cyclohexyl, cycloheptyl, chloromethyl, chloroethyl, bromopropyl, bromobutyl, chloro, fiuoro, bromo, iodo, methoxymethyl, ethoxyethyl, propoxymethyl, butoxypropyl, rnethoxy, ethoxy, n-propoxy, n-butoxy, isopentoxy, n-hexoxy, Z-ethylhexoxy, 3-methyloctoxy, decoxy, dodecoxy, octadecoxy, phenoxy, ethylphenoxy, propylphenoxy, dimethylphenoxy, phenylpropoxy, and the like. It is preferred that each R, individually, be hydrogen, alkyl, and/or alkoxy, and preferably still, that each R, individually, be hydrogen, lower alkyl, e.g., methyl, ethyl, npropy1, isobutyl, and/or lower alkoxy, e.g., methoxy, ethoxy, propoxy, n-butoxy, and the like. It is further preferred that the total number of carbon atoms in the substituents attached to the cyclic ester ring does not exceed twelve. Cycloalkyl and lower alkyl-substituted cycloalkyl radicals which have fromv Prior art attempts to polymerize gamma-butyrolactone and the substituted gamma-butyrolactones have been unsuccessful. Attempts to polymerize the cyclic esters, e.g., gamma-butyrolactones, beta-oxa-gamma-butyrolactones, and the like, in the process of this invention likewise have failed. Qne would postulate that the thermodynamic stability of these monomeric cyclic esters which contain five atoms in the lactone ring is much greater than the corresponding polymers, and'that thefree energy of interconversion is exceedingly 710W. Proviso states that the total number of organic substituents attached to the carbon atoms contained in the cyclic ester ring should not exceed four, and preferably should not exceed three. It has been observed that when the total number of organic substitutents on the cyclic ester ring approached four or more, then the polymerizability of the cyclic ester monomer in the process of the invention diminished drastically. Proviso (distatesthatfrom 2 to 4 continuously linked carbon atoms contained' in the cyclic ester ring can represent a portion of a saturated cycloaliphatic hydrocarbon nucleus which contains from 4 to 10 ring carbon atoms such as, for example, a saturated cycloaliphatic hydrocarbon nucleus. derived from cycloalkane, alkyl-substituted cycloalkane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, methylcyclopentane, methylcyclohexane, and the like. Thus, for example, the following illustrative cyclic esters would be included in this proviso:

v 2-oxa-5,7 ,7 -trimethylbicyclo [4.1.1 octan-3-one 2-oxablcyclo [3.2.2 ]nonan3-one 1 Proviso (2) States that the four R variables attached to any two adjacent carbon atoms contained in the.

W. H. Carothers, G. L. Borough, and F. J. van Natta, Jour. Amer, Chem. Soc, 54,761 (1932).

caprolactone,

4 pylbenzene, naphthalene and the like. To illustrate this proviso, the following compound is depicted structurally.

2,3,4,5tetrahydro-2-keto-benzoxepin In the structurally depicted compound immediately above, the four R variables which were attached to the carbon atoms designated by numerals 6 and 11 now represent a portion of the fused benzene ring, namely the carbon atoms designated by the numerals 7, 8, 9, and 10. The following compound further illustrates proviso e).

2-(2-hydroxymethylphenyl)benzene carboxylic acid lactone mon0methyl-, monoethyl-, monoisopropyl-, monobutyl monohexyl-, monodecyl-, and monododecyl-delta-valero lactones, and the like; the dialkyl-delta-valerolactoncs in which the two alkyl groups are substituted on the same or different carbon atoms in the cyclic ester ring, e.g., the dimethyl-, diethyl-, diisopropyl-, dipentyl-, and di-n-octyldelta-valerolactones, and the like; the monoalkyl-, dialkyl-, or trialkyl-epsilon-caprolactones, e.g., the monomethyl-, monoethyl-, monoisopropyl-, monohexyl-, monon-octyl-, dimethyl-, diethyl-, di-n-propyl-, diisobutyl-, din-hexyl-, trimethyl-, triethyl.-, and tri-n-propyl-epsiloncaprolactones, and the like; the monoalkoxyand dialkoxy-delta-valerolactones and epsilon-caprolactones, e.g., monomethoxy-, monoethoxy-, monoisopropoxy-, dirnethoxy-, diethoxy-, and dibutoxy-delta-valerolactones and epsilon-caprolactones, and the like. Further illustrative cyclic esters include 3-ethyl-2-keto-1,4-dioxane, gamma(l -'isopropyl 4 methylcyclohexyl) epsilon- 3-bromo-2,3,4,5-tetrahydrobenzoXepin-2- one, 2-,(2-hydroxyphenyl)benzene. carboxylic acid lac tone, lO-hydroxyundecanoic 'acid lactone, 2,5,6,7-tetrahydrobenzoxepin-Z-one, one, 4oxa-14-hydroxytetradecanoic acid lactone, alpha, alpha bis(chloromethyl) propiolactone, 1,4dioxane- 2-one, 3-n-propyl-2 -keto-1,4-dioxane, 3-(2-ethylhexyl)- 2-keto-I,4-dioxane, and the like. Illustrative subclasses of cyclic esters which are eminently suitable in the proc ess .of the instant invention include the unsubstituted lactones and the oxalactones which contain from 6 to 8 atoms in the lactone ring, preferably delta-valerolactone, epsilon-caprolactone, the keto-dioxanes, and the like; the monoand polyalkyl-substituted lactones and oxalactones which contain from '6 to 8 atoms in the lactone ring, preferably the monoand poly-lower .alkyl-delta-valerolactones, epsilon-caprolactones, and their corresponding oxalactones wherein the alkyl substituent(s) contains from 1 to 4 carbon atoms, and the like; and the mono- 9-oxabicyclo[5.2.2]undecan-8-.

i l I and polyalkoxy-substituted lactones and oxalactoneswhich contain from 6 to 8 atoms in the lactone ring, preferably the monoand poly-lower alkoxy-delta-valerolactones, epsilon-caprolactones, and their corresponding oxalactones wherein the alkoxy substituent(s) contains from 1 to 4 carbon atoms.

The unsubstituted and substituted delta-valerolactones, epsilon-caprolactones, zeta-enantholactones, and higher membered lactones, e.g., monoand polyalkyl-substituted delta-valerolactones, monoand polyalkoxy-substituted delta-valerolactones, monoand polycycloalkyl-substituted delta-valerolactones, aryl-substituted delta-valerolactones, monoand polyhaloalkyl-substituted delta-valerolactones, monoand polyalkyl-substituted epsiloncaprolactones, monoand polyalkoxy-epsilon-caprolactones, aryl-substituted epsilon-caprolactones, monoand polyhaloalkyl-substituted epsilon-caprolactones, monoand polyalkyl-substituted zeta-enantholactones, and various other lactones described previously can be prepared by reacting the corresponding cyclic ketone with an anhydrous solution comprising peracetic acid and acetone. It is desirable to add the peracetic acid solution to an excess of ketone, e.g., 5 to 1 molar ratio of ketone to peracetic acid, in a still kettle maintained under reflux. The pressure can be adjusted so as to provide a kettle temperature of, for example, about 70 C. Acetone, acetic acid by-product, and minor amounts of ketone-can be continuously removed throughout the addition period. Subsequently, the lactone product can be recovered from the still kettle by conventional techniques such as by distillation.

Stoll and Rouv report the preparation of lactones which contain up to 22 carbon atoms in the lactone nucleus by a process which comprises contacting the corresponding terminal hydroxy saturated aliphatic monocarboxylic acid with benzene-sulfonic acid catalyst in boiling benzene. These authors also report the preparation of other lactone such as 14-alkyl-l4-hydroXy-tetradecanoic acid lactone, e.g., 14-hydroxypentadecanoic acid lactone, and oxa-15-hydroxypentadecanoic acid lactone, e.g., l2-oxa-IS-hydroxypentadecanoic acid lactone. Palomaa and Tonkola teach the preparation of 3-oXa-6- hydroxyhexanoic acid lactone by heating the corresponding terminal hydroxy saturated aliphatic monocarboxylic acid. The preparation of 2-keto-l,4-dioxane, 3-alkyl-2- keto-1,4-dioxane, polyalkoxy-substituted delta-valerolactone, monoand polyalkyl-substituted delta-valerolactone, alkoxyalkyl-substituted delta-valerolactone, etc. is recorded by Carothers et all The preparation of dialkylsubstituted dihalo-substituted lactone, e.g., gmma, deltathe formula II ABH;

wherein A is lithium, sodium, potassium, rubidium, or cesium; wherein B is boron, aluminum, gallium, and in- *Helv. Chim. Acta, 18,1087 (1935).

Berx, 66, 1629 (1933).

7 See footnote 1.

B Zhur. Obshchei Khim, 24, 1439 (1954).

Bern, 68B, 1170 (1935). .1. Gen. Chem. USSR, 27, 1459 (19o7 3'. Amer, Chem. Soc, 77, 5601-6 (19cc).

dium; or wherein H represents hydrogen. Illustrative double metal hydrides contemplated as catalysts include, among others, lithium aluminum hydride, lithium borohydride, sodium borohydride, sodium aluminum hydride, potassium borohydride, and the like.

The double metal hydrides are employed in catalytically significant quantities. In general, a catalyst concentration in the range of from about 0.001, and lower, to

about 10, and hi her, weight percent, based on the weight of total monomeric feed, is suitable. A catalyst concentration in the range of from about 0.01 to about 3.0

Weight percent is preferred. A catalyst'concentration in the range of from about 0.05 to about 1.0 weight percent is highly preferred. For optimum results, the particular catalyst employed, the nature of the monomeric reagent(s), the operative conditions under which the poly merization reaction is conducted, and other factorswill largely determine the desired catalyst concentration.

The polymerization reaction can be conducted over a wide temperature range. Depending upon various factors such as the nature of the monomeric reagent(s) employed, the particular catalyst employed, the concentration of the catalyst, and the like, the reaction temperature can be as low as 20 C., and lower, and as high as 250 C., and higher. A suitable temperature range is from about 0 to about 225 C. A reaction temperature in the range of from about 20 to about 200 C. is preferred.

The polymerization reaction preferably occurs in the liquid phase, and to this extent sufi'icient pressure is employed to maintain an essentially liquid reaction mixture regardless Whether or not an inert normally-liquid organic vehicle is employed. Preferably, the polymerization reaction is conducted under an inert atmosphere, e.g., nitrogen, butane, helium, etc. The ultimate molecular Weight of the resulting polymer will depend, to an extent, upon various factors such as the temperature, the choice and concentration of the catalyst, the use and amount of an inert normally-liquid organic vehicle(s), and the like.

In general, the reaction time will vary depending on the operative temperature, the nature of the monomeric cyclic esters employed, the particular catalyst and the concentration employed, the use of inert normally-liquid organic vehicle, and other factors. The reaction time can vary from several seconds to several hours, or more, depending on the variables illustrated above.

It is preferred to conduct the polymerization reaction in the essential absence of impurities which contain active hydrogen since the presence of such impurities tends to deactivate the catalyst and/or increase the induction period. The minimization or essential avoidance of im-. purities such as Water, carbon dioxide, aldehydes, ketones, etc., is highly desirable. t is also preferred that the polymerization reaction be conducted under substantially anhydrous conditions.

When polymerizing an admixture containing at least two different cyclic esters, the proportions of said cyclic esters can vary over the entire range. Broadly the con centration of each monomeric cyclic ester is in the range of from about 3 to about 97 weight percent, based on the total weight of said cyclic esters. The preferred range is from about 15 to about weight percent. Admixtures containing epsilon-caprolactone and monoand/or polyalkyl-substituted epsilon-caprolactone (including isomeric mixtures thereof) are highly preferred as tarting materials in the process of the invention. Admixtures containing different monoand/or polyalkyl-substituted epsilon-caprolactones (including isomeric mixtures of the same and/or difierent monoand/or polyalkyl-substituted epsilon-caprolactoncs) also are highly preferred.

The polymers of this invention can be prepared via the bulk polymerization, suspension polymerization, or the solution polymerization routes. The polymerization reaction can be carried out in the presence of an inert normally-liquid organic vehicle such as, for example,

, ethers of ethylene glycol, of propylene glycol, of diethylene glycol, and the like; normally-liquid saturated hydrocarbons including the open chain, cyclic, and alkyl-substituted cyclic saturated hydrocarbons such as hexane, heptane, various normally-liquid petroleum hydrocarbon fractions, cyclohexane, the alkylcyclohexanes, decahydronaphthalene, and the like. If desired, a mixture of mutuallymiscible inert normally-liquid organic vehicles can be employed.

The process of the invention can be executed in a batch, semi-continuous, or continuous fashion. The re action vessel can be a glass vessel, steel autoclave, elongated metallic tube, or other equipment and material em-' ployed in the polymer art. The order of addition of catalyst and monomeric reagent(s) does. not appear tobe critical. *A suitable procedure is to add the catalyst to the reaction zone containing the monomeric reagent(s) and inert organic vehicle, if any. it is highly preferred that the catalyst be added as a suspension or dispersion in an inert normally-liquid organic vehicle such as, for instance, the inert normally-liquid saturated aliphatic and cycloaliphatic hydrocarbons, e.g., hexane, heptane, octane, cyclohexana. alkylcyclohexane, decahydronaphthalene, and the like. Incremetal addition of catalyst to the reaction zone can be employed. If desired, the above procedure can be reversed, that is, the monomeric reagent(s) per se or as a solution or suspension in an inert organic vehicle can be added to the reaction zone which preferably contains the catalyst as a suspension or dispersion in an inert normally-liquid organic vehicle. Also, the catalyst, reagent(s), and inert organic vehicle, if any, can be added to the reaction zone simultaneously.

The reaction zone (be it a closed vessel or an elongated techniques such as by heating said reaction product under reduced pressure. Removal of unreacted monomeric reagent(s) and/or inert organic vehicle can be accomplished by mechanical means such as treatment of the reaction product in a Marshall Mill and the like. The polymer product also can be recovered from the reaction 'product by washing said reaction product with 'an inert normally-liquid organic vehicle, e.g., heptane, and sub- .sequently drying same under reduced pressure at slightly elevated'temperatures. Another route involves dissolution in a first inert organic vehicle, followed by the addition of a second inert organic vehicle which is miscible with the first vehicle but which is a non-solvent for the polymer product, thus precipitating the polymer product. If desired, the reaction product can be dissolved in an inert organic vehicle such as acetone, and the like, followed by the addition of sufiicient water to the resulting solution, said water being miscible with said inert organic vehicle but being a non-solvent for the waterrinsoluble polymer thereby precipitating the polymer product. Recovery of the precipitated polymer can be effected by filtration, decantation, etc., followed by drying same as indicated previously.

The linear polyester products resulting from'the process of the invention can be characterized by the followingrecurring structural unit:

unit.

wherein the variables R, A, x, y, and 2, have the same values as shown in Formula I supra. Of course, the five provisos enumerated as (a) through (2) set forth in the discussion of Formula I supra likewise apply to the structural unit designated at Formula III above. In addition, as intimated previously, the molecular weights of the polyester products can range from about several hundred to about several thousand. The ultimate molecular weight and properties of the polyester products will depend, in the main, upon the choice of the cyclic ester(s) and catalyst, the concentration of the catalyst, the operative conditions employed, e.g., temperature, etc., the purity of the monomeric reagent(s) and catalyst, the use and amount of an inert normally-liquid organic vehicle, and the like.

It is readily apparent that the linear homopolymers are essentially characterized by the same recurring unit which falls within the scope of Formula 111 supra. The copolymers, terpolymers, etc., on the other hand, can contain as little as 1,0 weight percent, and lower, and upwards to 99 weight percent, and higher, of the same recurring Desirable polymers are those in which the Weight percent of the different recurring units is in the range of from about 3 to about 97. In the highly preferred copolymers the weight percent of the two diflerent recurring units is in the range of from about 15 to about 85.

The polymers obtained by the process of the invention are a useful class of polyester compounds. These polymers can range from viscous liquids to tough solids. The polymers in the range of from very viscous liquids to relatively low molecular weight, wax-like solids are useful in the preparation of cosmetics, polishes, and waxes, and as thickening agents for various lubricants. The polymers can be employed to size cellulosic material or they can be used as anti-static agents in the treatment of fibrous materials. They can also be employed as protective coatings and/or impregnants. The solid polymers areuseful for the production of various shaped articles such ,as brush handles, buttons, lamp bases, toys, and the like.

In passing, it should be noted thatone: apparent advantage afforded by the practice of the invention is the preparation of copolymers, terpolymers, etc., whose physical characteristics can be tailor-made to fit desired fields of applications and uses. In other Words, by adjusting the concentration of the monomeric charge to a particular polymerization system, copolymers, terpoly-t mers, etc., which cover. a wide spectrum of properties and characteristics can be prepared, e.g'., soft, rubbery polymers to tough, solid polymers; i

In the illustrative operative examples to follow, the polymeric product is sometimes described as possessing a certain reduced viscosity value. By thisterm, i.e., reduced viscosity, is meant a value obtained by dividing the specific viscosity by the concentration of the polymer in the solution, the concentration being measured in grams of polymer per milliliters of solvent at a given temperature. ing the diifercnce between the viscosity of the solution and the viscosity of the solvent by .the viscosity of the solvent. The reduced viscosity valueis an indication of the molecular weight of the polymer. Unless otherwise indicated, the reduced viscosity'value was determined at 30 C.

Also, in the illustrative operative example below,the polymerization reaction was generally conducted under an inert atmosphere, e.g., nitrogen. The reaction vessel and contents, i.e., cyclic ester(s), catalyst and inert or- The specific viscosity is obtained by divid- 9.. ganic vehicle, if any, were maintained, usually under agitation, in a constant temperature, e.g., 90 C., or the reaction vessel containing the cyclic ester(s) was maintained, usually under agitation, in a constant temperature and subsequently the catalyst was added thereto. Since EYAMPLE 1 A. To a reaction vessel maintained under a nitrogen atmosphere and which contained epsilon-caprolactone, there was charged lithium aluminum hydride in an amount so as to give an admixture containing 0.1 weight percent lithium aluminum hydride, based on the weight of said epsilon-caprolactone. The reaction vessel then was placed in a constant temperature bath maintained at 90 C. Within one hour the mechanical stirrer ceased due to the high viscosity of the contents in the reaction vessel. Thereafter, the polymer product was recovered. Therewas obtained a white, soft, waxy, solid hemopoi mer which possessed a reduced viscosity value of 0.3 (measured at 0.2 gram of polymer in 100 ml. of benzene).

B. In an analogous manner as above, when beta,gamma dimethoxy delta valerolactone is substituted for epsilon-caprolactone and contacted with 1.0 weight percent sodium borohydride, there is obtained a solid polymer.

EXAMPLE 2 Thereafter, the polymer product was recovered. There was obtained a white, waxy, brittle solid homopolyme'r which possessed a reduced viscosity value of 0.2 (measured at 0.2 gram of polymer in 100 ml. of benzene).

B. In an analogous manner as above, when potassium borohydride is substituted for sodium borohydride in an amount so as to give an admixture which contains 0.4 weight percent of potassium borohydride, based on the weight of epsilon-caprolactone, essentially the same -re.'

sults are obtained.

EXAMPLE 3 10 atmosphere and which contains an isomeric mixture of methyl-epsilon-caprolactone, there is charged sodium aluminum hydride, in an amount so as to give an admixture containing 0.5 weight percent sodium aluminum hydride, based on the total weight of methyl-epsiloncaprolactone. The isomeric mixture contains, by weight, approximately 30 percent gamma-methyl-epsilon-caprolactone, about'30 percent epsilon-methyl-epsilon-caprolactone, and about 40 percent beta-methyland deltamethyl-epsilon-caprolactone. This isomeric lactone mixture is prepared by reacting a mixture of 2-methyl-, 3-methyl-, and 4-methylcyclohexanone with peracetic acid. The reaction vessel then is placed in a constant temperature bath maintained at 90 C. for a period of 12 minutes. Thereafter, the polymeric product is recovered. There is obtained a very viscous liquid product.

B. In an analogous manner as above, when Z-bromo- 2-(3'-bromopropyl)-5-hydroxypentanoic acid lactone is substituted for the isomeric mixture of methyl-epsilon A. To a reaction vessel maintained under a nitrogen atmosphere and which contains an isomeric mixture composed of a major proportion by weight of gamma-octylepsilon caprolactone and a minor proportion by weight of epsilon-octyl-epsilon-caprolactone, there is charged lithium aluminum hydride dispersed in heptane in an amount so as to give an admixture containing 0.8 weight percent lithium aluminum hydride, based on the total weight of octyl-epsilon-caprolactone. The reaction vessel then is placed in a constant temperature bath maintained at 90 C. for a period of 40 minutes. There is obtained a very viscous liquid product.

B. In an analogous manner as above, when 2,3,4,5- tetrahydrobenzoxepin-2-one is substituted for the isomeric mixture of octyl-epsilon-caprolactones and contacted with 1.0 weight percent sodium borohydride, there is obtained a solid polymer.

EXAMPLE 6 A. To a reaction vessel maintained under a nitrogen atmosphere and which contains delta-valerolactone, there is charged sodium borohydride dispersed in petroleum ether in an amount so as to give an admixture containing 0.5 weight percent sodium borohydride, based on the weight of said delta-valerolactone. The reaction vessel then is placed in a constant temperature bath maintained at 90 C. for a period of 30 minutes. Thereafter, the

v polymeric product is recovered. There is obtained a A. To a reaction vessel maintained under a nitrogen atmosphere and which L contains 'epsilon-caprolactone, there is charged potassium borohydride in an amount so as to give an admixture containing 0.3 weight percent potassium borohydride, based on the weight of said epsilon-caprolactone. The reaction vessel then is placed in a constant temperature bath maintained at 90 C. for a period of 20 minutes. Thereafter, the polymeric prodnot is recovered. There is obtained a white solid.

B. In an analogous manner as above, when gamma(1- isopropyl 4 methylcyclohexyl) epsilon-caprolactone is substituted for epsilon-caprolactone and contacted with 0.7 Weight percent sodium aluminum hydride, a viscous liquid product is obtained.

tough, solid homopolymer.

B. in an analogous manner as above, when 3-ethyl-2- keto-l,4-dioxane is substituted for delta-valerolactone and contacted with 1.0 weight percent lithium borohydride, a very viscous liquid is obtained.

EXAMPLE 7 A. To a reaction vessel maintained under a nitrogen atmosphereand which contains beta-methyl-delta-valerolactone'(redistilled, boiling point 137 C. at 1.5 mm. of Hg; n;; of 1.4480) there is charged lithium aluminum hydride in an amount so as to give an admixturecontaining 1.0 weight percent lithium aluminum hydride, based on the weight of said beta-methyldelta-valerolactone. The reaction vessel then is placed in a constant temperature bath which is maintained at C. for a period of.

1 I EXAMPLES 8-10 In Examples 8 through 10, various copolymers are prepared by polymerizing an admixture of two lactones in the presence of lithium aluminum hydride. The procedure employed is similar to that set forth immediately preceding the operative examples. The pertinent data and results are recorded in Table I below.

12 EXAMPLES 15-16 In Examples 15 and 16, various copolymers are prepared by contacting, at 90 C., a mixture of epsiloncaprolactone and delta-valerolactone with 0.4 weight percent of lithium aluminum hydride, based on the total Weight of the lactone feed. The procedure employed is similar to that set forth immediately preceding the opera- T able I Example 7 Catalyst Temp., Time, Description of Number Lactone Charge 1 Concen- 0. Min. Copolymer tration 2 70 epsilon-caprolactone/SO beta-methyl- 0.4 90 9 Tough solid.

delta-valerolaetone. 8O epsilon-caprolactone/2O beta-methyl- 0.4 9O 9 Tough, film-forming delta-valerolactone. solid. 10 85 epsilon-caprolactone/15 beta-methyl- 0.4 90 18 White, waxy solid;

. deltavalerolactone.

1 Parts by Weight, 2 Weight percent catalyst, based on total weight of lactone charge.

Nora-B eta-methyl-delta-valerolactone redistilled; 13.15. 137 C. at 1.5 mm

EXAMPLE 11 25 A. To a reaction vessel maintained under a nitrogen atmosphere and which contains 'zeta-enantholactone, there is charged potassium borohydride in an amount so as to give an admixture containing 0.5 weight percent potassium borohydride, based on the weight of said zeta- 3 EXAMPLES 12-13 In Examples 12 and 13, the procedure employed is similar to that set forth immediately preceding the operative examples. The pertinent data and results are recorded in Table II below.

. of Hg; m) of 1.4480.

tive examples. The pertinent data and results are recorded in Table III below.

" Table III Ratio of I Epsilon- Time, .Description oi Example Number Caprnlactone Min. Copolymer to Delta- Valerolactone 1 15 :80 15 'White, hard solid. 16 80:20 10 Tough solid.

! Ratio is in parts by weight.

EXAMPLE 17 A. To a reaction vessel maintained under a nitrogen atmosphere and which contains a mixture of 50 parts by weight of epsilon-caprolactone and 50 parts by weight of mixed octyl-epsilon-caprolactones, there is charged lithium aluminum hydride in an amount so as to give an Table II Example Catalyst Temp., Time, Description of Numbcr Lactone Charge 1 Concen- C. Min. Polyester tration 2 12. V zeta-enmtholactone/W epsi- LiAlH 0. 110 18 Hard, white solid.

lon-eapr0lactone. I

13 20 zeta-enantholactone/SO epsi- LiAlH 0. 50 110 12 Tough, white solid.

lon-caprolactone,

. '1 Admirture of two lactones is expressed as parts by Weight.

2 Weight percent catalyst, based on total weight of lactone charge.

N0rE.-Zeta-enantholactone redistilled; B.P. 72 C. at 4 mm. of Hg; an of 1.4689.

"EXAMPLE 14 A. To a reaction vessel maintained under a nitrogen atmosphereand which contains 2-keto-l,4-dioxa'ne, there is charged lithium borohydride in, an amount so as .to give an admixture containing 0.3 weight percent lithium b0ro-- hydride, based on the weight of said 2-keto-l',4-dioxane. The reaction vessel then is placed in a constant temperature bath maintained at 90 ,C. for a period of about one hour. Thereafter, the polymeric product is recovered.

There is obtained a tough, solid polymer. 7 a

admixture containing 0.5 Weight percent lithium aluminum hydride, based on thetotal weight of the lactone feed. The mixed octyl-caprolactones comprise a major proportion by'weight of gamma-octyland a minor proportion by weight of epsilon-octyl-epsilon-caprolactones. The reaction vessel then is placedvin a constant temperature bath maintained-at90 C. for a period of one hour. Thereafter, the reaction product is dissolved in acetone and reprecipitatedin water There is obtained a waxy copolymer.

B. In an analogous manner as above, when equal parts by weight .of 9-oxabicyclo[5.2.2]undecan-8-one and 1,4- dioxane-2-one are employed as the monomeric feed and contacted with 1.5 weight percent potassium borohydride,

essentially similar results are obtained.

EXAMPLE 18 To a reaction vessel maintained under a nitrogen atmosphere and which contains equal parts, by weight, of 2,4- diniethyl-4-methoxymethyl-S-hydroxypentanoic acid lactone and epsilon-caprolactone, there is charged sodium borohydride in an amount so as to give an admixture containing 0.5 weight percent sodium borohydride, based on the total Weight of the monomeric charge. The reac-. tion vessel then is placed in a constant temperature bath maintained at 90 C. for a period of 30 minutes. Thereafter, the reaction product is dissolved in acetone and reprecipitated in water. There is obtained a soft, solid copolymer.

EXAMPLE 19 A. To a reaction vessel maintained under a nitrogen atmosphere and which contains ortho-(Z-hydroxyethyl): phenylacetic acid lactone, there is charged lithium borohydride in an amount so as to give an admixture containing 0.50 weight percent lithium borohydride, based on the weight of said ortho-(2-hydroxyethyl)-phenylacetic acid lactone. The reaction vessel then is placed in a constant temperature bath maintained at 90 C. for a period of 40 minutes. There is obtained a solid polymer.

B. In an analogous manner'as above, when cis-3-oxabicyclo[5.4.0]undecan-4-one is substituted for ortho-(2- hydroxyethyl)-phenylacetic acid lactone and contacted .With 1.0 weight percent lithium aluminum hydride, essentially similar results are obtained.

EXAMPLE 20 I To a reaction vessel maintained under a nitrogen atmosphere and which contained delta-valerolactone, there was charged potassium borohydride in an amount so as to give an admixture containing 0.6 weight percent potassium borohydride, based on the weight of said deltavalerolactone. The reaction vessel then was placed in a constant temperature bath maintained at 90 C. for a period of 4 hours. Thereafter, the temperature was raised to 150 C. and maintained thereat for an additional 16 hours. There was obtained a viscous liquid product which possessed a reduced viscosity value of 0.05 (measured at 0.2 gram of polymer in 100 ml. of chloroform). 7 Although the invention has been illustrated by the preceding examples, the invention is not to be construed as'limited to the materials employed in the above exemplary examples, but rather, the invention encompasses the generic area as hereinbefore disclosed. Various modifications and embodiments of this invention can be made without departing from the spirit and scope thereof.

What is claimed is: a

1. A process which comprises polymerizing a cyclic wherein each R, individually, is selected from the group consisting of hydrogen, alkyl, aryl, alkaryl, aralkyl, cycloalkyl, halo, haloalkyl, alkoxyalkyl, alkoxy, aryloxy, a portion of an aromatic hydrocarbon nucleus which nucleus is fused to the cyclic ester ring, and a portion of a saturated cycloaliphatic hydrocarbon nucleus which nucleus contains from 4 to 10 carbon atoms and which is fused to the cyclic ester ring; wherein A is selected from the group consisting of an oxy group, a thio group, and a divalent saturated aliphatic hydrocarbon group, wherein x is an integer in the range of from 1 to inclusive; wherein y is an integer in the range of from 1 to 15 inclusive; and wherein z is an integer selected from the group consisting of zero and one; with the provisos that 14 (a) the sum of x-l-y-l-z cannot equal three, (b) the total number of atoms forming the cyclic ester ring does not exceed 18, and (c) the total number of organic substituents attached to the carbon atoms contained in the cyclic ester ring does not exceed four; with from about 0.001 to about 10 weight percent, based on the total weight of cyclic ester of a compund characterized by the following formula:

2. A process which comprises polymerizing an admixture comprisingat least two cyclic esters which are characterized by the following formula:

wherein each R, individually, is selected from the group consisting of hydrogen, alkyl, aryl, alkaryl, aralkyl, cycloalkyl, halo, haloalkyhalkoxyalkyl, alltoxy, aryloxy, a portion of an aromatic hydrocarbon nucleus which nucleus is fused to the cyclic ester ring, and a portion of a saturated cycloaliphatic hydrocarbon nucleuswhich nucleus contains from 4 to 10 carbon atoms and which is fused to the cyclic ester ring; wherein A is selected from the group consisting of an oxy group, a thio group, and a divalent saturated aliphatic hydrocarbon group; wherein x is an integer in the range of from 1 to 15 inclusive; wherein y is an integer in the range of from 1 to 15 inclusive; and wherein z is an integer selected from the group consisting of zero and one; with the provisos that (a) the sum of x-l-y-l-z cannot equal three, (b) the total number of atoms forming the cyclic ester ring does not exceed 18, and (c) the total number of organic substituents attached to the carbon atoms contained in the cyclic ester ring does not exceed four; with from about 0.001 to about 10 weight percent, based on the total weight of cyclic ester, of a compound characterized by the following formula:

ABH,

wherein A is selected from the group consisting of lithium, sodium, potassium, rubidium, and cesium; wherein B is selected from the group consisting of boron, aluminum, gallium, and indium; and wherein His hydrogen; under substantially anhydrous conditions; for a period of time sufficient to produce a, polymer.

3. A process which comprises polymerizing deltavalerolactone with from about 0.01 to about 3.0 weight percent, based on the weight of said delta-valerolactone, of a catalyst characterized by the following formula:

ABH,

wherein A is selected from the group consisting of lithium, sodium, potassium, rubidium, and cesium; wherein B is selected from the group consisting of boron, aluminum, gallium, and indium; and wherein H is hydrogen; at a temperature in the range of from about 0 C. to about 225 C.; under substantially anhydrous conditions; and for a period of time suflicient to produce a polymer.

4. A process which comprises polymerizing an alkylsubstituted delta-valerolactone with from about 0.01 to about 3.0 weight percent, based on the weight of said alkyl-substituted delta-valerolactone, of a catalyst characterized by the following formula:

V ABH, V wherein A is selected from the group consisting of lithium,

ABH, wherein A is selected from the group consisting of lithium,

' sodium, potassium, rubidium, and cesium; wherein B is selected from the group consisting of boron, aluminum, gallium, and indium; and wherein H is hydrogen; at a temperature in the range of from about C. to about 225 C.; under substantially anhydrous conditions; and for a period of time sufficient to produce a polymer.

7. A process which comprises polymerizing an alkylsubstituted epsilon-*caprolactone with from about 0.01 to about 3.0 weight percent, based on the weight of said alkyl-substituted epsilon-caprolac'tone, of a catalyst characterized by the following formula:

ABH 7 wherein A is selected from the group consisting of lithium,

sodium, potassium, rubidium, and cesium; wherein B is selected from the group consisting of boron, aluminum,

gallium, and indium; and wherein H is hydrogen; at a temperature in the range of from about 0 C. to about 225 C.; under substantially anhydrous conditions; and for a period of. time suflicient to produce a polymer.

8. A process which comprises polymerizing a monomeric lactone admixture comprising delta-valetolactone and an alkyl-substituted delta-valerolactone with from about 0.01 to about 3.0 weight percent, based on the total weight of the monomeric lactone feed, of a catalyst characterized by the following formula:

. ABH, wherein A is selected from the group'consisting of lithium,

' sodium, potassium, rubidium, and cesium; wherein B is selected from the group consisting of boron, aluminum, gallium, and indium; and wherein H is hydrogen; at a temperature in the range of from about 0 C. to about 225 C.; under substantially anhydrous conditions; and for a period of time sufiicient to produce a polymer.

9. A process which comprises polymerizing a monomeric lactone admixture comprising delta-valerolactone and epsilon-caprolactone with from about 0.01 to about 3.0 weight percent, based on the total weight'of the monomeric lactone feed, of a catalyst characterized by the following formula:

' 'ABH wherein A is selected from the group consisting of lithium, sodium, potassium, rubidium,

and cesium; wherein B is selected from the group consisting of boron, aluminum, gallium, and indium; and wherein H is hydrogen; at a temperature in the range of from about 0, C. to about 225 C.; under substantially anhydrous conditions; and for a period of time sufiicient to produce a polymer.

10. A process which comprises polymerizing a monomeric lactone admixture comprising delta-valerolactone and an alkyl-substituted epsilon-caprolactone with from about 0.01 to about 3.0 weight percent, based on the total weight of the monomeric lactone feed; of a catalyst characterized by the following formula:

ABH; wherein A is selected from the group consisting of lithium, sodium, potassium, rubidium, and cesium; wherein B eselected from the group consistingof boron, aluminum,

1'6 gallium, and indiumyand wherein H is hydrogen; at a temperature in the range of from about 0 C. to about 225 C.; under substantially anhydrous conditions; and for a period of time suflicient to produce a polymer.

11. A process which comprises polymerizing a monomeric lactone admixture comprising epsilon-caprolactone and an alkyl-substituted delta-valerolactone with from about 0.01 to about 3.0 weight percent, based on the total weight of the monomeric lactone feed, of a catalyst characte'rized by the following formula:

ABH,

wherein A is selected from the group consisting of lithium, sodium, potassium, rubidium, and cesium; wherein B is selected from the group consisting of boron, aluminum, gallium, and indium; and wherein H is hydrogen; at a temperature in therange of from about 0 C. to about 225 C.;under substantially anhydrous conditions; and for a period of time 'suflicient to produce a polymer.

'12. A process which comprises polymerizing a monomeric lactone admixture comprising epsilon-caprolactone and an alkyl-sub'stituted epsilon-caprolactone with from about 0.01 to about 3.0 weight percent, based on the total weight of the monomeric lactone feed, of a catalyst characterized by the following formula:

wherein A is selected from the group consisting of lithium, sodium, potassium, rubidium, and cesium; wherein B is selected from the group consisting of boron, aluminum, gallium, and indium; and wherein H-is hydrogen; at a temperature in the range of from about 0 C. to about 225 C.; under substantially anhydrous conditions; and for a period of time sufficient to produce a polymer.

13. A process which comprises polymerizing a monomeric lactone admixture comprising an alkyl-substituted epsilon caprolactone and an alkyl-substituted delta-valerolactone with from about 0.01 to about 3.0 weight percent,'-based on the total weight of the monomeric lactone feed, of a catalyst characterized by the following formula:

. ABH;

wherein A is selected from the group consisting of lithium, Sodium, potassium, rubidium, and cesium; wherein B is selectedfrom'the group consisting of boron, aluminum, gallium, and indium; and wherein H is hydrogen; at a temperature in the range of from about 0 C. to about 225 C.; under substantially anhydrous conditions; and for a period of time suflicient to produce a polymer. i

14. A process which comprises polymerizing a menomeric lactone admixture comprising two alkyl-substituted delta-valerolactones with from about 0.01 to about 3.0

' .weight percent, based on the total Weight of the monolowing formula:

meric lactone feed, of a catalyst characterized by the fol- ABH; i a

V wherein A is selected from the group consisting of lithium sodium, potassium, rubidium, and cesium; wherein B is 7 selected from the groupiconsisting of boron, aluminum,

gallium, and indium; and wherein H' is hydrogen; at a temperature in the range of from about 0 C. to about 225 C.; under substantially anhydrous conditions; and for a period of time suflicient to produce a polymer.

15. A process which comprises polymerizing-a monomeric lactone admixture comprising two'alkyl-substituted epsilon-caprolactones with from about 0.01 to about 3.0 weight percent, based on the total weight of the monomeric lactone feed, of a catalyst characterized by the following formula:

ABH, wherein A is selected from the group consisting of lithium, sodium, potassium, rubidium, and cesium; wherein B is selected from the group consisting of boron, aluminum, gallium,'and indium; and wherein H is hydrogen; at a temperature in the range of from, about 0C. to about 17 1?) 225 C.; under substantially anhydrous conditions; and 2,809,958 Barnes et al Oct. 15, 1957 for a period of time suflicient to produce a polymer. 2,848,441 Reynolds et a1. Aug. 19, 1958 2,890,208 Young et a1. June 9, 1959 References Cited in the file of this patent 2,921,051 Amborski et a1 Jan. 12, 1960 UNITED STATES PATENTS 5 FOREIGN PATENTS 2558547 Eckey June 1951 766,347 Great Britain Jan. 23, 1957 2,720,506 Caldwell Oct. 11, 1955 

1. A PROCESS WHICH COMPRISES POLYMERIZING A CYCLIC ESTER CHARACTERIZED BY THE FOLLOWING FORMULA: 